1. Field of the Invention
The present invention relates to an organic electroluminescence (hereinafter, referred to as organic EL) display apparatus, and, in particular, to an organic EL display apparatus that uses electroluminescence elements made of an organic material as luminescing elements in luminescent pixels, and a method of controlling the same.
2. Description of the Related Art
A flat panel display with a thin and light body is expected to play a major role as a multimedia device in the future. Such a typical flat panel display may be a liquid crystal display, an organic EL display, or the like. At present, the most popular and widely applied flat panel display is the liquid crystal display. However, this liquid crystal display has some problems that may prevent further improvement of its display quality.
More specifically, it needs to increase its emission luminance in order to obtain a higher brightness because a conventional liquid crystal display requires a backlight. If the emission luminance of the backlight is increased, the display brightness of the conventional liquid crystal display increases. However, it is difficult to completely shield light of the backlight by the liquid crystals thereby causing deterioration of display performance of black color. Furthermore, because the maximum brightness of the liquid crystal display is determined by the backlight, its contrast is inevitably determined by the brightness of the backlight. Therefore, not alike a display using CRT, it is difficult to intentionally control its contrast and brightness by any method other than by means of input signals.
Furthermore, the liquid crystal display is of a type that holds information written into pixels for a period of time corresponding to one field. Accordingly, motion picture display quality of the liquid crystal display is inferior compared to that of the CRT. This is because that, while a light of display in the CRT is impulsive, a light of display in the liquid crystal display changes in a stepwise form basically due to the holding operation for one field period (in practice, it changes exponentially due to a response time of the device), thereby causing blurriness to be perceived when displaying the motion picture.
On the other hand, the organic EL display uses, as its luminescing (light-emitting) element in a luminescent pixel, an organic EL element that can yield a brightness of several hundreds to several tens thousands nit at a driving voltage equal to or less than 10 V. Further, because the organic EL display has such advantages that it is a self-luminescing type with no viewing angle dependency, has a high contrast ratio and an excellent motion picture display performance compared to that of the hold type display. Accordingly, it is expected to be a promising flat panel display of the next generation.
As a method of driving the organic EL display, a passive matrix method and an active matrix method are known. In order to realize a large-scaled and high-resolution display, in the case of the passive matrix method, because an luminescing period of each pixel decreases with an increasing number of scanning lines (i.e., the number of pixels in the vertical direction), it is required for a respective organic EL element in each pixel to luminesce instantaneously at a high brightness. On the other hand, in the case of the active matrix-addressed method, because each pixel maintains its luminescing for a period of one frame, it is easier to realize the large-scaled and high-resolution display.